Conplast® P509 is a high-performance, chloride-free water reducing admixture developed by Fosroc for improving the quality, strength, and durability of concrete. It is formulated using advanced polymeric materials based on hydrolysed carbohydrate derivatives, designed to deliver maximum cement particle dispersion without causing unwanted side effects such as segregation or excessive air entrainment.
This admixture is suitable for a wide range of concrete applications where improved workability, enhanced strength, and long-term durability are required. Conplast P509 is particularly effective in structural concrete, reinforced concrete, prestressed concrete, and large pours where consistent performance and controlled setting time are critical.
Performance & Working Mechanism
Conplast P509 functions by efficiently dispersing cement particles throughout the concrete mix. This dispersion reduces internal friction between particles, allowing the same level of workability to be achieved with less water. As a result, the water-cement ratio is significantly reduced, leading to increased concrete density, improved strength development, and lower permeability.
At low to medium dosages, Conplast P509 acts as a normal water-reducing plasticiser. At higher dosages, it can function as a retarding water-reducing admixture, extending initial setting time while maintaining workability. This dual functionality makes it highly versatile for varying site conditions and ambient temperatures.
Key Advantages
Increased Strength
Conplast P509 enables water reduction of up to 10%, which directly contributes to higher early and ultimate compressive strength without increasing cement content. This results in cost-effective mix designs and stronger structural elements.
Improved Durability
By lowering the water-cement ratio, the concrete becomes denser and less permeable. This significantly improves resistance to:
Water penetration
Aggressive chemicals
Shrinkage cracking
Long-term environmental exposure
Enhanced Workability
Concrete treated with Conplast P509 exhibits improved slump and flow characteristics without loss of strength. This allows for easier placement, better compaction, and superior surface finish, even in congested reinforcement areas.
Faster & Easier Construction
Improved workability enables quicker placing and compaction, reducing labor effort and construction time. In large pours, extended setting times at higher dosages help avoid cold joints.
Chloride-Free & Safe
Conplast P509 contains nil chloride content (as per IS 456), making it safe for:
Reinforced concrete
Prestressed concrete
Sulphate-resisting cement
Marine and coastal structures
Compatibility
Conplast P509 is compatible with:
All types of Portland cement
Portland slag cement
Blended cements
(Except high-alumina cement)
It is also compatible with other Fosroc admixtures, provided each product is added separately to the mix.
Typical Performance Results
Based on M30 concrete mix trials:
Increased slump from 40 mm to 100 mm without changing water-cement ratio
28-day compressive strength increased from 38.7 N/mm² to 43.3 N/mm² at same W/C ratio
Strength increased up to 48.9 N/mm² when water-cement ratio was reduced
These results demonstrate Conplast P509’s ability to improve either workability or strength, depending on project requirements.
Application & Dosage
The optimum dosage should be determined through site trials. Typical dosage ranges between:
160 ml to 500 ml per 100 kg of cement
At dosages above 400 ml per 100 kg of cement, Conplast P509 may act as a retarding plasticiser. The admixture should be measured accurately and added directly to the mixer, preferably with the mixing water. If water is added in stages, the admixture should be introduced during the final stage.
Curing & Overdosing
Standard curing methods such as water ponding, spraying, or wet hessian should be used. Where water curing is difficult, curing compounds like Fosroc Concure WB are recommended.
Overdosing may extend the initial setting time; however, the ultimate strength will not be reduced and may increase if water reduction is utilized effectively.
Packaging, Storage & Shelf Life
Conplast P509 is supplied in:
200 L drums
20 L cans
5 L containers
It has a minimum shelf life of 12 months when stored in cool, shaded conditions and protected from extreme temperatures.
Health & Safety
Conplast P509 is non-toxic and non-flammable. In case of skin contact, wash with clean water. If contact with eyes occurs, rinse immediately with plenty of water and seek medical advice.
Conclusion
Fosroc Conplast® P509 is a reliable, proven, and cost-effective water-reducing admixture that enhances concrete strength, durability, and workability while ensuring safety for reinforced and prestressed structures. Its chloride-free formulation, flexible dosage range, and compatibility with various cement types make it an ideal choice for modern construction projects demanding quality, performance, and long-term durability.